A continuum theory for the fractures in brittle and ductile solids

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In the physics of fracture, brittle solids, such as glass, suddenly break when a sharp crack grows on the cleavage plane. In contrast, ductile solids, such as copper, are soft and resistant to cleavage. I will present a continuum theory of fracture in solids, where the brittle and the ductile solids are particular limits. For instance, in this theory, the stress field explains the type of fracture, while the thermodynamic condition generalises Griffith’s equation to include the shielding of the dislocations at the crack-tip. When only the plastic strains determine the fracture mechanism, this thermodynamic condition proves the Orowan-Irwin formula. Also, this theory can be used to solve applied problems, such as the embrittlement of nickel-based superalloys at high temperatures.